[英]Converting QImage to YUV420P pixel format
有人先前解决了这个问题吗? 我需要简单快速的方法将QImage :: bits()缓冲区从RGB32转换为YUV420P像素格式。 你能帮助我吗?
libswscale是ffmpeg项目的一部分,它优化了例程来执行颜色空间转换,缩放和过滤。 如果你真的想要速度,我会建议使用它,除非你不能添加额外的依赖。 我实际上没有测试过这段代码,但这里是一般的想法:
QImage img = ... //your image in RGB32
//allocate output buffer. use av_malloc to align memory. YUV420P
//needs 1.5 times the number of pixels (Cb and Cr only use 0.25
//bytes per pixel on average)
char* out_buffer = (char*)av_malloc((int)ceil(img.height() * img.width() * 1.5));
//allocate ffmpeg frame structures
AVFrame* inpic = avcodec_alloc_frame();
AVFrame* outpic = avcodec_alloc_frame();
//avpicture_fill sets all of the data pointers in the AVFrame structures
//to the right places in the data buffers. It does not copy the data so
//the QImage and out_buffer still need to live after calling these.
avpicture_fill((AVPicture*)inpic,
img.bits(),
AV_PIX_FMT_ARGB,
img.width(),
img.height());
avpicture_fill((AVPicture*)outpic,
out_buffer,
AV_PIX_FMT_YUV420P,
img.width(),
img.height());
//create the conversion context. you only need to do this once if
//you are going to do the same conversion multiple times.
SwsContext* ctx = sws_getContext(img.width(),
img.height(),
AV_PIX_FMT_ARGB,
img.width(),
img.height(),
AV_PIX_FMT_YUV420P,
SWS_BICUBIC,
NULL, NULL, NULL);
//perform the conversion
sws_scale(ctx,
inpic->data,
inpic->linesize,
0,
img.height(),
outpic->data,
outpic->linesize);
//free memory
av_free(inpic);
av_free(outpic);
//...
//free output buffer when done with it
av_free(out_buffer);
就像我说的,我没有测试过这段代码,因此可能需要进行一些调整才能使其正常工作。
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